17 February 2010 The Silicon Vertex Detector of the Belle II Experiment VCI 2010 M.Friedl, T.Bergauer, I.Gfall, C.Irmler, M.Valentan (HEPHY Vienna)

The Silicon Vertex Detector of the Belle II Experiment 2Markus Friedl (HEPHY Vienna)17 February 2010 Introduction Belle II: The Future SuperSVD Components APV25 & Time Resolution Readout System Summary Contents

The Silicon Vertex Detector of the Belle II Experiment 3Markus Friedl (HEPHY Vienna)17 February 2010 Linac Belle KEKB KEKB and KEK Asymmetric machine: 8 GeV e - on 3.5 GeV e + Center of mass energy: Y(4S) (10.58 GeV) High intensity beams (1.6 A & 1.3 A) Integrated luminosity 1 ab -1 recorded by end of 2009 ~1 km in diameter Mt. Tsukuba KEKB Belle Linac About 60km northeast of Tokyo

The Silicon Vertex Detector of the Belle II Experiment 4Markus Friedl (HEPHY Vienna)17 February 2010 „…the two particle detectors BaBar at Stanford, USA and Belle at Tsukuba, Japan, both detected broken symmetries…“ (Press Release of the Swedish Academy) 2008 Nobel Prize in Physics T. Maskawa M. Kobayashi

The Silicon Vertex Detector of the Belle II Experiment 5Markus Friedl (HEPHY Vienna)17 February 2010 µ / K L detection 14/15 lyr. RPC+Fe CsI(Tl) 16 X 0 Si vertex detector 4 lyr. DSSD SC solenoid 1.5 T 8 GeV e GeV e + Aerogel Cherenkov counter n=1.015~1.030 Central Drift Chamber small cell +He/C 2 H 5 TOF counter Belle Detector (1999–2010)

The Silicon Vertex Detector of the Belle II Experiment 6Markus Friedl (HEPHY Vienna)17 February 2010 The Present: SVD2 – Overview 4 layers (6/12/18/18 ladders), r = 2.0…8.8 cm 17°…150° polar angle coverage 246 double sided silicon detectors (DSSDs), 0.5 m 2 overall active area VA1TA readout chip (Viking variant; 800ns shaping time) channels in total

The Silicon Vertex Detector of the Belle II Experiment 7Markus Friedl (HEPHY Vienna)17 February 2010 Introduction Belle II: The Future SuperSVD Components APV25 & Time Resolution Readout System Summary

The Silicon Vertex Detector of the Belle II Experiment 8Markus Friedl (HEPHY Vienna)17 February 2010 KEKB/Belle upgrade (2010–2013) Aim: super-high luminosity ~8  cm -2 s -1  1  BB / year LoI published in 2004; TDR is presently being written Refurbishment of accelerator and detector required

The Silicon Vertex Detector of the Belle II Experiment 9Markus Friedl (HEPHY Vienna)17 February 2010 Belle II SVD Upgrade (2010–2013) Present SVD limitations are –occupancy (currently ~10% in innermost layer)  need faster shaping –dead time (currently ~3%)  need faster readout and pipeline Needs Silicon Vertex Detector with –high background tolerance –pipelined readout –robust tracking –low material budget in active volume (low energy machine) Current SVD is not suitable for Belle II Ultimately 40-fold increase in luminosity (~8  cm -2 s -1 )

The Silicon Vertex Detector of the Belle II Experiment 10Markus Friedl (HEPHY Vienna)17 February 2010 Present SVD2 Layout 4 straight layers of 4" double-sided silicon detectors (DSSDs) Outer radius of r~8.8 cm Up to 3 sensors are ganged and read out by one hybrid located outside of acceptance

The Silicon Vertex Detector of the Belle II Experiment 11Markus Friedl (HEPHY Vienna)17 February 2010 SuperSVD Layout Geometry optimization is underway New central pixel double-layer using DEPFET Strip layers extend to r~14 cm Every sensor is read out individually (no ganging) to maintain good S/N  chip-on-sensor concept Double-layer of DEPFET pixels 4 layers of double- sided strip sensors

The Silicon Vertex Detector of the Belle II Experiment 12Markus Friedl (HEPHY Vienna)17 February 2010 Introduction Belle II: The Future SuperSVD Components APV25 & Time Resolution Readout System Summary

The Silicon Vertex Detector of the Belle II Experiment 13Markus Friedl (HEPHY Vienna)17 February 2010 Double-sided Silicon Strip Detectors Only 3 different sensor designs for SuperSVD (2 x, 1 x ) 6” prototypes ordered from Hamamatsu (rectangular) and Micron (trapezoidal) Currently in production, expected in April and summer Atoll p-stop designTrapezoidal sensor with test structures

The Silicon Vertex Detector of the Belle II Experiment 14Markus Friedl (HEPHY Vienna)17 February 2010 APV25 Readout Chip Developed for CMS (LHC) by IC London and RAL (70k chips installed) 0.25 µm CMOS process (>100 MRad tolerant) 40 MHz clock (adjustable), 128 channels 192 cell analog pipeline  no dead time 50 ns shaping time  low occupancy Low noise: 250 e + 36 e/pF  must minimize capacitive load!!! Multi-peak mode (read out several samples along shaping curve) Thinning to 100µm successful Schematics of one channel

The Silicon Vertex Detector of the Belle II Experiment 15Markus Friedl (HEPHY Vienna)17 February 2010 Origami – Chip-on-Sensor Concept Chip-on-sensor concept for double-sided readout Flex fan-out pieces wrapped to opposite side (hence “Origami“) All chips aligned on one side  single cooling pipe Prototype for 4” DSSD (later with 6” sensors) Side View (below)

The Silicon Vertex Detector of the Belle II Experiment 16Markus Friedl (HEPHY Vienna)17 February th Open Meeting of the Belle II Collaboration First Origami Module Top and bottom side Origami concept (4” sensor) Prototype completed in August 2009 Successfully evaluated in lab and beam tests

The Silicon Vertex Detector of the Belle II Experiment 17Markus Friedl (HEPHY Vienna)17 February 2010 Sketch of the Outermost Ladder (Layer 6) Composed of 5 x 6” double-sided sensors Center sensors have Origami structure Border sensors are conventionally read out from sides Connector (Nanonics) Structural element (CF) Cooling pipe Flex circuits Electronics for border sensor ca. 60cm

The Silicon Vertex Detector of the Belle II Experiment 18Markus Friedl (HEPHY Vienna)17 February D Rendering (preliminary) Carried by ribs made of carbon fiber and Rohacell Averaged material budget: 0.58% X 0 Cooling options under study

The Silicon Vertex Detector of the Belle II Experiment 19Markus Friedl (HEPHY Vienna)17 February 2010 Introduction Belle II: The Future SuperSVD Components APV25 & Time Resolution Readout System Summary

The Silicon Vertex Detector of the Belle II Experiment 20Markus Friedl (HEPHY Vienna)17 February 2010 APV25 – Hit Time Reconstruction Possibility of recording multiple samples (x) along shaped waveform (feature of APV25) Reconstruction of peak time (and amplitude) by waveform fit Will be used to remove off-time background hits Measurement

The Silicon Vertex Detector of the Belle II Experiment 21Markus Friedl (HEPHY Vienna)17 February 2010 Measured Hit Time Precision Results achieved in beam tests with several different types of Belle DSSD prototype modules (covering a broad range of SNR) ns RMS accuracy at typical cluster SNR ( ) Working on implementation in FPGA (using lookup tables) – simulation successful (TDC error subtracted) Origami Module

The Silicon Vertex Detector of the Belle II Experiment 22Markus Friedl (HEPHY Vienna)17 February 2010 Aim: Occupancy Reduction With hit time reconstruction, we can cope with 40-fold increase in luminosity

The Silicon Vertex Detector of the Belle II Experiment 23Markus Friedl (HEPHY Vienna)17 February 2010 Introduction Belle II: The Future SuperSVD Components APV25 & Time Resolution Readout System Summary

The Silicon Vertex Detector of the Belle II Experiment 24Markus Friedl (HEPHY Vienna)17 February 2010 Readout System Prototype readout system exists Verified in several beam tests Basis for future SVD system shown below

The Silicon Vertex Detector of the Belle II Experiment 25Markus Friedl (HEPHY Vienna)17 February 2010 Prototype Readout System Repeater Box Level translation, buffering FADC+PROC (9U VME) Digitization, zero-suppression, hit time reconstruction

The Silicon Vertex Detector of the Belle II Experiment 26Markus Friedl (HEPHY Vienna)17 February 2010 Beam Tests KEK (Apr 2005) PSI (Aug 2005, Aug 2006) KEK (Nov 2007, Nov 2008) CERN (June 2008, September 2009)

The Silicon Vertex Detector of the Belle II Experiment 27Markus Friedl (HEPHY Vienna)17 February 2010 Introduction Belle II: The Future SuperSVD Components APV25 & Time Resolution Readout System Summary

The Silicon Vertex Detector of the Belle II Experiment 28Markus Friedl (HEPHY Vienna)17 February 2010 Summary KEKB is the highest luminosity machine in the world Belle experiment acknowledged by Physics Nobel Prize 2008 Upgrade of KEKB and Belle ( ) –40-fold increase in luminosity –Needs upgrades of all subdetectors New, enlarged Silicon Vertex Detector –DEPFET pixel double-layer –Plus 4 strip layers Strip Detector R&D –Origami chip-on-sensor concept for low-mass DSSD readout –Readout with hit time reconstruction for improved background tolerance (up to 100x occupancy reduction w.r.t. now) –Implementation in FPGA hardware (using lookup tables) SVD